From Making sense of the federation protocol landscape comes a good graphical representation of where the different Federated Identity Standards mesh.
This is slightly inaccurate. The Shibboleth layer should actually extend further upwards into the Identity Service Provider layer, but hey, this is the best graphical representation I've seen as to how some of the different Federated Identity standards inter-relate.
Right now, about 50 higher education sites are piloting the software. To date, there are no deployments outside higher education.
And now that I think about it, iTunes U would be an excellent service to Shibbolize. Sign into iTunes U with your Case credentials and be taken to the Case iTunes section. Makes perfect sense to me.